In optical systems, image artifacts result when the light source or excitation emission and the detector (e.g., eye or camera) are imprecisely focused at the same point in the object. Such image artifacts may be observable as elongation of the objects either perpendicular to the line (e.g., a defocused excitation system) or parallel to the line (e.g., a defocused imaging system).
The disclosed devices and methods may be employed to reduce or eliminate chromatic or comatic variations in the location of the excitation or emission in an optical system (e.g., a confocal microscope) by enhancing parfocality.